Describe the different forms taken by carbon and nitrogen, and the reservoirs where they are found.
Earth and Space Science
Earth Systems, Structures, and Processes
In prior grades students learned about planet Earth as an interacting system of solids, liquids, and gases, and about the water cycle, the rock cycle, and the movement of crustal plates. In grades 9-11 students learn how the uneven heating of Earth’s surface causes differences in climate in different parts of the world, and how the tilt of Earth’s axis with respect to the plane of its orbit around the Sun causes seasonal variations. Students also learn about the essential biogeochemical cycles that continuously move elements such as carbon and nitrogen through Earth systems. These major ideas about energy inputs and outputs in and around the Earth help students understand Earth as a dynamic system.
Earth is a system that contains essentially a fixed amount of each stable chemical element existing in different chemical forms. Each element on Earth moves among reservoirs in the solid Earth, oceans, atmosphere, and organisms as part of biogeochemical cycles driven by energy from Earth’s interior and from the Sun.